This invention relates generally to an attachment for an asphalt paving machine and more specifically to an attachment for such a machine which will permit the laying of a gutter adjacent to and integral with a roadway surface which is being simultaneously laid by the machine.
In asphalt paving operations requiring a gutter strip adjacent to and co-extensive with the roadway surface, it is traditional to pave the roadway first and in a separate operation pave the narrow gutter beside it. Such a second operation adds considerably to the expense of the paving operation not only in respect of time taken but also in respect of equipment and energy used.
The gutter forming operation is a fairly precise one since the width and cross-sectional profile of gutters beside highways are carefully controlled by Government regulations. In Ontario, for example, regulations often require that the gutter be 32 inches in width and have a cross-sectional profile such that the half of the gutter nearest the roadway is downwardly sloped, away from the roadway, two inches over its width, and the other half of the gutter is then upwardly sloped from the lowest point of the first half a total of 6 inches over its width. This gives an uneven "V"-shaped cross-sectional profile or contour to the gutter. The first, downward slope is relatively gradual to prevent a driver, who may have accidentally steered a wheel onto the gutter from losing control of the car before he can return that wheel to the normal surface of the roadway. The outer, upward slope of the gutter is steeper to minimize the spillover of water which may be running along the gutter, over the outer edge of the gutter down into the shoulders. When this occurs, erosion of the shoulders results with consequent undermining of the roadbed and damage to the edge surfaces of the roadway.
Many attachments for asphalt spreading machines have been proposed in the prior art for a variety of purposes. Indeed, the automatic screed extension, to which the attachment of the present invention may be attached, is itself an attachment to such machine. North American asphalt paving machines are customarily made for laying ten foot wide strips of asphalt. In order to pave half the width of a 22 foot or 24 foot wide roadway, however, it is necessary to provide for an extension of the strip which the machines can pave. This is done by means of an automatic extension which is secured to and adjustable sideways on the original screed of the paving machine. Using such an extension, it is possible then to pave the required width of one-half the road surface, one-half the road surface normally being paved at one time in an asphalt highway paving project. Such a screed extension is described and illustrated in Canadian Pat. No. 779,653 of J. D. Layton, issued Mar. 5, 1968, this extension being used on a paver to be towed behind a dump truck. Curb and gutter paving machines, of general background interest, are described and illustrated in Canadian Pat. Nos. 502,483 of E. S. Clark, et al., issued May 18, 1954; Canadian Pat. No. 596,171 of W. E. Canfield, et al., issued Apr. 12, 1960 and Canadian Pat. No. 768,408 of J. Sigmund, issued Oct. 3, 1968.
U.S. Pat. No. 3,680,451 of R. D. Birtchet, issued Aug. 1, 1972 describes a pivotable wing attachment for an automatic screed extension which enables either, but not a combination of, upward or downward sloping of a margin of the roadway during paving. The wing is made up of an elongated blade having a substantially straight and horizontal lower edge and a second, shorter elongated blade extending parallel to the first blade but cut at an angle so that the departure point of the sloping portion relative to the horizontal portion of the roadway remains the same when the angle of the main blade is changed. The Birtchet device however is not intended to be an attachment for forming a gutter beside a roadway and indeed would be unable to operate as such since, if it were modified to provide both downward and upward slopes to form an appropriate gutter, the device would be unable to provide a sufficient slope to the outside portion of the gutter, i.e. the backing, to satisfy Government requirements. The reason for this is that the screed backing, in order to provide adequate support for the device, must be so low that only a very limited upward angle could be achieved. In addition, such attachment is not readily movable since the pivot bolt, being positioned so close to the asphalt being spread, would become extremely hot and difficult to work during the paving operation.
It is an object of the present invention to provide an attachment for an asphalt machine which may be readily attached or detached therefrom, which will enable laying of a gutter simultaneously with the laying of the roadway surface. It is a further object of the invention to provide an attachment which will enable laying of a gutter integral with a roadway surface and having a cross-sectional profile complying with Government standards and regulations.